Conversion of hydrocarbon oils



May 25, 1937. K. swARTwooD CONVERSION OF HYDROCARBON OILS Filed May 29,1955 Tracfl'onaof INVENTOR. jfwzzzetiz .jy'zz/oocl, BY gi ATTORNEY.

AIIIHHH H||||||||| Tu Wha Ce Patented May 25, 1937 UNITED STATES PATENTOFFICE CONVERSION F HYDROCARBON OILS Application May 29, 1933, SerialNo. 673,332

2 Claims.

This invention `particularly refers to an improved process and apparatusfor the simultaneous conversion of hydrocarbon oils of differentcharacteristics, the different oils each being subjected to treatmentunder independently controlled conversion conditions most suitable tosecure high yields of the desired products.

In one specific embodiment, the invention comprises subjecting arelatively low-boiling hydrocarbon oil,.such as motor fuel of inferiorantiknock value, naphtha, kerosene orvkeros'ene distillate, pressuredistillate bottoms, or the like, or fractions or mixtures of suchmaterials, to the desired conversion conditions of elevated temperatureand superatmospheric pressure in a heating coil, discharging the streamof heated oil from the heating coil, and commingling therei with astream of cooler high-boiling hydrocarbon oilsuch as crude petroleum,topped crude, fuel oil, gas oil or the like for the purpose of coolingthe lower boiling oils and retarding or arresting their conversion,subjecting the commingled oils to vaporization at substantially reducedpressure relative to that employed in the heating coil, separating theresulting vapors Vand residual liquid conversion products, subjectingthe vapors to fractionation whereby their insufficiently convertedcomponents are condensed as reflux condensate, subjecting fractionatedvapors of the desired end-boiling point to condensation, co1- lectingand separating the resulting distillate and gas, subjecting said refluxcondensate resulting from .fractionation of the vaporous conversionproducts of theV process to independently controlled less severeconversion conditions of elevated temperature and superatmosphericpressure in a separate heating coil and communicating reaction chamber,separating the resulting vaporous and residual liquid conversionproducts preferably at substantially reduced pressure relative to thatemployed in the reaction chamber and subjecting the vapors tofractionation, together With the vapors resulting from the rst mentionedcracking and vaporizing operations.

Several alternative flows are possible within the scope ofthe presentinvention, some of which depart in detail from the specific embodimentabove described. The accompanying diagrammatic drawing, whichillustrates one specific form of ap-` paratus embodying the essentialfeatures of the` present` invention, and the following description ofthe drawing, will serve to more clearly illustrate the` operation of theinvention as well as several of the many possible alternate flows andoperating conditions, which alternatives, however, are not to beconsidered equivalent.

Referring to the drawing, a relatively light hydrocarbon oil chargingstock of the nature heretofore indicated is supplied through line I andvalve 2 to pump 3 by means of which it is fed, in the case illustrated,through line 4 and valve 5 to heating coil E. It will be understood thatthis charging stock may, when desired, be preheated in any well knownmanner, prior to its introduclo tion into the heating coil, althoughprovisions for accomplishing such preheating are not illustrated in thedrawing.

A furnace 'l of any suitable form encloses heating coil '6 and suppliesthe required heat to bring 15 the oil passing through the heating coilto the desired conversion temperature, preferably at a substantiallysuperatmospheric pressure and the heated oil is preferably maintained ata conversion temperature near the maximum attained in the heating coilfor a suicient length of time to substantially complete the desireddegree of conversion in this zone. The highly heated low-boiling oil isdischarged from heating coil 6 through line 8 and valve 9 and may passthrough valve I0 in this line into vaporizing chamber I I.

Simultaneously another oil of higher average boiling point than thatsupplied to heating coil 6 and of the nature heretofore indicated issupplied through line I2 and valve I3 to pump I4 from which it isdischarged through line I5 and may pasls, all or in part, through valveI6 in this line into line 8. The high-boiling charging stock may bepreheated, when desired, to any desired temperature below that at whichits appreciable conversion will occur, prior to its introduction intoline B. This may be accomplished in any well known manner and as oneapproved method of accomplishing this all or any regulated portion ofthe heavy charging stock may be diverted from line I5 through line Iland valve I8 into heat exchanger I9 wherein it is preheated by indirectcontact with vaporous conversion products of the process, as will belater more fully described, the preheated charging stock passing fromheat eX- changer I9 through line 2li and valve 2I back into line I5 andthence into line 8, together with that portion, if any, of the heavycharging stock not passed through the heat exchanger. The re1- ativelyhigh-boiling charging stock commingled in line `8 with the highly heatedlower boiling oil from heating coil 6 serves to cool the latter to thedesired degree which is regulated by the temperature and the volume ofhigher boiling oil supplied to line 8, the cooling preferably being ofsufficient extent to substantially retard or arrest further conversionof the low-boiling oils from the heating coil so that the conversiontime as well as the temperature and pressure conditions to which thelow-boiling oils are subjected is under positive control. An appreciablereduction in the pressure imposed upon the stream of highly heatedlow-boiling oils discharged from heating coil 5 is accomplished, asdesired, either prior or subsequent to the introduction of the coolingoil into line S, Valves 9 and I being provided for this purpose. Thereduction in pressure serves to assist cooling of the heated oil andalso assists vaporization of the commingled high-boiling and low-boilingoils in vaporizing chamber II.

Chamber II, as already indicated, is preferably operated at asubstantially reduced pressure relative to that employed in heating coil6, the pressure employed in this zone being regulated to securevaporization of substantially all of the commingled oils supplied tothis zone with the exception of any high-boiling components of a heavyresidual nature unsuitable for conversion, together with the refluxcondensate, which operation will be later more fully described. Residualliquid remaining unvaporized in chamber I I may be withdrawn therefromthrough line 22 and valve 23 to cooling and storage or to any desiredfurther treatment. Vaporous products pass from chamber I i through line24, valve 25 and line 26, in the case illustrated, into heat exchangerI9 wherein they may serve to 'preheat high-boiling charging stocksupplied to this zone, as previously indicated, the vaporous productspassing from the heat exchanger through line 2l and valve 28 tcfractionation in fractionator 29. It will be understood that heatexchanger I9 may be bypassed, when desired, by all or a portion of thevaporous products from chamber I I, although the well known means foraccomplishing this are not shown in the drawing. Any condensate removedfrom the vapors passing through heat exchanger I9 may be withdrawntherefrom through line 62 and valve 63 and may, for example, be returnedby well known means, not illustrated in the drawing, either tovaporizing chamber II or to fractionator 29.

As an alternate method of operation whereby vaporizing chamber II may beeliminated and which may be utilized when the nature of the chargingstocks and the conversion conditions employed in heating coil 6 are suchthat the stream of commingled high-boiling and low-boiling oils in line8 contains no appreciable quantity of deleterious residual materials,the commingled stream of heated oils instead of passing to vaporizingchamber II may be diverted from line 8 through line 26 and Valve 2 toheat exchanger I9 and thence to fractionator 29. When this method ofoperation is employed it may be desirable to utilize a heat exchanger inplace of heat exchanger I9 of a somewhat different type than thatillustrated in the drawing or, when desired, the heat exchanger may beeliminated.

The vaporous products supplied to fractionator 29 are subjected thereinto fractionation by any well known means whereby their insufficientlyconverted components boiling above the desired end-point of the finallight distillate product of the process are condensed as refluxcondensate which collects in the lower portion of the fractionator,together with any oil supplied to this zone in unvaporized state andpassing therefrom through line 39 and valve 3I to pump 32 by means cfwhich the reflux condensate is supplied through line 33 and valve 34 tofurther conversion in heating coil 35, as will be later described.

Fractionated vapors of the desired end-boiling point are withdrawn,together with uncondensable gas produced in the process, from the upperportion of fractionator 29 through line 36 and valve 31 and aresubjected to condensation and cooling in condenser 39. The resultingdistillate and uncondensable gas passes through line 39 and Valve 45 tocollection and separation in receiver 4I. Uncondensable gas may bereleased from the receiver through line 42 and valve 43. Distillate iswithdrawn from this Zone through line 44 and valve 45 to storage or toany desired further treatment. When desired, a regulated portion of thedistillate collected in receiver 4I may be withdrawn therefrom throughline 46 and valve 4l to pump 48 by means of which it is returned throughline 49 and valve 59 to the upper portion of fractionator 29, servingthe purpose of a cooling and refluxing medium to assist fractionation ofthe vapors and maintain the desired vapor outlet temperature from thefractionator, thus controlling the end-boiling point of the nal lightdistillate product withdrawn from receiver 4I.

Heating coil 35 is located in a furnace 5I of any suitable form by meansof which sufficient heat is supplied to the oil passing through theheating coil to subject it to the desired conversion ternperature,preferably at a substantial superatmospheric pressure and the heated oilis discharged through line 52 and valve 53, in the case illustrated,into reaction chamber 54, which is preferably also maintained at asubstantial superatmospheric pressure and, although not illust'rated inthe drawing, is preferably well insulated against the excessive loss ofheat by radiation so that conversion of the heated oil from heating coil35 and particularly its vaporous components may continue in this zone.

Both vaporous and liquid conversion products are withdrawn from thelower portion of chamber 54, in the case illustrated, through line 55and valve 56 and introduced into vaporizing chamber 5l', which ispreferably operated at a substantially reduced pressure relative to thatemployed in the reaction chamber by means of which further vaporizationof the liquid conversion products supplied thereto is accomplished.Residual liquid remaining unvaporized in chamber 51 may be withdrawntherefrom through line 58 and valve 59 to cooling and storage or to anydesired further treatment. The vaporous conversion products pass fromchamber 5'I through line 6U, valve 6I and line 21 to fractionation infractionator 29, together with the other material supplied to this zone,as previously described.

As another somewhat different method of operation which, although notillustrated in the drawing, may be utilized within the scope of thepresent invention, when chamber II is employed, the stream of vaporousand liquid conversion products from chamber 54 may be supplied tochamber Il instead of to chamber 57, thus eliminating the latter. Also,when desired, reaction chamber 54 may be eliminated by supplying theheated oil from heating coil 35 to chamber II by well known means, notshown in the drawing. This latter alternative is preferably employedonly when the nature of the oil supplied for conversion to heating coil35 is such that its desired degree of conversion may be substantiallycompleted with the heating coil without the necessity of separatingheavy liquid conversion products therefrom lin order to avoid excessivecoke formation and deposition in heating coil and/or the excessiveproduction of gas.

'Ihe conversion temperature employed at the outlet from the heating coilto which the lowboiling charging stock is supplied may range, forexample, from 950 to 1050 F., preferably with a substantialsuperatmospheric pressure, measured at this point, within the range of300 to 800 pounds, or more, per square inch. The substantially reducedpressure employed in the succeeding vaporizing chamber, when such a zoneis utilized, may range, for example, from 100 pounds, or thereabouts,per square inch, superatmospheric pressure down to substantiallyatmospheric pressure and this same range of pressures may be utilized inthe succeeding fractionating, condensing and collecting portions of thesystem. The heating coil to which the reux condensate from thefractionator is supplied for further conversion may utilize an outlettemperature ranging, for example, from 850 to 925 F., preferably with asubstantial superatmospheric pressure, measured at the outlet from theheating coil, of from 100 to 500 pounds, or thereabouts, per squareinch. 'Ihe reaction chamber, when such a zone is employed, may utilize asuperatmospheric pressure of from 100 to 500 pounds, or thereabouts, persquare inch and a substantially reduced pressure ranging from 100pounds, or thereabouts, to substantially atmospheric pressure ispreferred in the succeeding vap'orizing chamber.

As a specic example of the operation of the process of the presentinvention, as it Vmay be practiced in an apparatus such as illustratedand above described, the low-boiling charging stock is a Pennsylvaniadistillate of about 52 A. P. I. gravity which is subjected in theheating coil to a conversion temperature of approximately 980 F. at asuperatmospheric pressure of about 500 pounds per square inch and isthen cooled to a temperature of approximately '720 F., by pressurereduction and by commingling therewith the high-boiling charging stock,and the commingled oils are introduced into the vaporizing chamber,which is operated at a pressure of approximately 50 pounds per squareinch. The high-boiling charging stock, in this case, is a Mid-continenttopped crude of about 30 A. P. I. gravity and about equal quantities oflow-boiling and highboiling charging stocks are supplied to the system.The pressure employed in the vaporizing chamber is substantiallyequalized in the fractionating, condensing and collecting portions ofthe system. Reilux condensate from the fractionator is subjected in theseparate heating coil to which it is supplied, to an outlet temperatureof approximately 910 F. with a superatmospheric pressure 60 ofapproximately 300 pounds per square inch and the heated products arepassed through a reaction chamber operated at about the same pressure,the vaporous and residual liquid conversion products being subsequentlyseparated at reduced pressure and the vapors subjected to fractionation,together with the vapors from the preceding portion of the system.

An operation such as above described may yield, per barrel of totalcharging stock, approximately 67 percent of motor fuel having anantiknock value equivalent to an octane number of approximately 76 andabout 22 percent of residual oil of low B. S. content, the remaining 13percent, or thereabouts, based on the charging stock being chargeableprincipally to gas and unaccountable loss.r

I claim as myl invention:

1. A process for the simultaneous reforming of light hydrocarbon oilcontaining gasoline fractions of inferior anti-knock value and for theconversion of hydrocarbon oil heavier than gasoline into gasoline, whichcomprises subjecting the light oil while flowing in a restricted streamthrough a heating coil to cracking conditions of temperature andpressure adequate to enhance the anti-knock value of said gasolinefractions contained therein, cooling the thus heated light oil promptlyupon discharge from the coil to below cracking temperature bycommingling therewith said heavier oil while at below crackingYtemperature and by pressure reduction thereon,

thereby heating the heavier oil to distillation temperature, separatingthe commingled oils into vapors and residue and fractionating the formerto condense heavier fractions thereof, heating resultant reuxcondensate, while flowing in a restricted stream through a secondheating coil,4

to a lower cracking temperature than the light oil in thefirst-mentioned heating coil and then passing the same through areaction Zone maintained under cracking conditions and effecting furtherconversion therein, fractionating resultant vapors in admixture with therst-named vapors whereby insuniciently cracked fractions thereof arereturned to the second heating coil in said reflux condensate, and nallycondensingI the fractionated vapors.

2. A hydrocarbon Voil conversion process which comprises passing arelatively light oil through a heating coil and subjecting the sametherein to cracking conditions of temperature and pressure, comminglinga relatively cool and heavy oil with the cracked light oil promptly upondischarge of the latter from the coil and cooling the heated light oilto below cracking temperature, separating the resultant mixture intovapors and residue and fractionating the former to condense heavierfractions thereof, passing resultant reflux condensate through a secondheating coil and subjecting the same therein to milder cracking than thelight oil in the first-named coil, then passing the heated refluxcondensate through a reaction zone maintained under cracking conditionsof temperature and pressure and continuing the cracking of the reuxcondensate in this zone, discharging the cracked products from thereaction zone into a reduced pressure separating Zone and thereinseparating the vaporous from unvaporized products, fractionating thevaporous products in admixture with the first-named vapors, and nallycondensing and collecting the fractionated vapors.

KENNETH SWARTWOOD.

